Injecting my UnitOfWork into my Repository Constructor - nhibernate

Question

Im very new but on a quest to learn nhibernate and DI with structuremap so am making an app to test everything out.
I am having some problems injecting my unitofwork into my base repository. I create a unitofwork on every request then either commit or rollback at the end. But when tryin to inject into my base repository its always null when i go to use it in my methods. More specifically i get this error: "Object reference not set to an instance of an object". Any ideas what im doing wrong and if this is the correct route i should be going?
Many thanks in advance.
Base Repository:
public abstract class Repository<T> : IRepository<T>
{
public readonly IUnitOfWork _unitOfWork;
public Repository(IUnitOfWork UnitOfWork)
{
UnitOfWork = _unitOfWork;
}
public Repository() {}
public void Save(T obj)
{
_unitOfWork.CurrentSession.Save(obj);
}
}
StructureMap registry thats set in my application_start:
public class NHibernateRegistry : Registry
{
public NHibernateRegistry()
{
For<IUnitOfWork>().HybridHttpOrThreadLocalScoped().Use<UnitOfWork>();
For<ISession>().HybridHttpOrThreadLocalScoped().Use(context => context.GetInstance<ISessionFactory>().OpenSession());
For<ISessionFactory>().Singleton().Use(NHibernateSessionFactory.GetSessionFactory());
}
}
Update:
The baserepository is inherited by specific repositorys ie ArticleRepository then im injecting that into my aspx pages on application_start. Then my aspx page inherits a basepage where the buildUp takes place. And i access the repository like this:
public IArticleRepository ArticleRepo { get; set; }
public void SaveThing()
{
ArticleRepo.Save(object);
}
This gets called on application_start:
public class Bootstrapper
{
public static void BootStrap()
{
ObjectFactory.Configure(x =>
{
x.AddRegistry<NHibernateRegistry>();
x.AddRegistry<WebRegistry>();
});
}
}
And in the webregistry:
For<IArticleRepository>().Use<ArticleRepository>();

Answer 1

There is a good chance your ArticleRepository doesn't have a constructor that takes an IUnitOfWork as a parameter make sure you have the following
public class ArticleRepository : Repository<Article>
{
public ArticleRepository(IUnitOfWork unitOfWork) : base(unitOfWork)
{
}
...
}
Remember Strcuture map uses the greediest constructor on the class that it instantiates. Since your abstract repository class will never be instantiated it will not use its constructors. I would also suggest not having any default constructors if your classes need to have their dependencies injected that way. Less chance for errors that way.

Answer 2

public readonly IUnitOfWork _unitOfWork;
public Repository(IUnitOfWork UnitOfWork)
{
UnitOfWork = _unitOfWork;
}
I think you mean to write
public readonly IUnitOfWork _unitOfWork;
public Repository(IUnitOfWork UnitOfWork)
{
_unitOfWork = UnitOfWork;
}
You were assigning the local variable to the parameter instead of the parameter to the local variable.
Edit: Also you should write your parameter with a lowercase U 'unitOfWork' instead of 'UnitOfWork'